UN secretary-general Ban Ki-moon and former US vice-presidential candidate Sarah Palin have joined the condemnation of a small US church which plans to mark the anniversary of the September 11 attacks by burning a pile of Korans.

The Dove World Outreach Centre in Florida says it will burn the Korans as a warning to radical Islam, ignoring appeals by US authorities and condemnation by governments around the world.

UN spokesman Farhan Haq said Mr Ban believed the planned book burning contradicted the efforts of UN and could endanger aid workers in Afghanistan.

"The secretary-general is deeply disturbed by reports of a small religious group which plans to burn copies of the Koran," Mr Haq said.

"Such actions cannot be condoned by any religion. They contradict the efforts of the United Nations and many people around the world to promote tolerance, intercultural understanding and mutual respect between cultures and religions."

Ms Palin called the proposed burning an "insensitive and an unnecessary provocation" and "antithetical to American ideals".

"People have a constitutional right to burn a Koran if they want to, but doing so is insensitive and an unnecessary provocation - much like building a mosque at Ground Zero," she said.

"It will feed the fire of caustic rhetoric and appear as nothing more than mean-spirited religious intolerance. Don't feed that fire.

"If your ultimate point is to prove that the Christian teachings of mercy, justice, freedom, and equality provide the foundation on which our country stands, then your tactic to prove this point is totally counter-productive."

"We want them to know if they're in America, they need to obey our law and constitution and not slowly push their agenda upon us," he told the CBS television channel.

Mr Jones has indicated he was praying for guidance on whether to go ahead with the incendiary event, but it appeared the evangelical church was determined it would take place.

"As of right now, we feel that this message is that important. We are still determined to do it," he said.

US secretary of state Hillary Clinton has denounced the plans as "disgraceful" amid fears it will spur an angry backlash in the Islamic world, and could endanger the lives of allied and US troops in Afghanistan.

The event by the obscure evangelical church, said to have about 50 members, has thrust an unwanted spotlight on the normally quiet town of some 124,000 people situated in north-central Florida.

Mr Jones, a gun-toting pastor who has headed the church since 2001 and has acknowledged receiving death threats, is also the author of a book entitled Islam Is Of The Devil.

He has said he wants to honour the memory of the almost 3,000 people killed by Al Qaeda militants in the 9/11 attacks on the United States.

The US State Department has called Mr Jones' church "a very small fringe group" which does not represent the views of the US or Americans as a whole.

The scheme has already inflamed passions in the Islamic world, and could trigger further anger as it may coincide with the Eid al-Fitr feast that marks the end of the holy fasting month of Ramadan also due this weekend.

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